fix deprecated warning

I was getting this warning when in Debug mode.
```
Creation of dynamic property OCA\FirstRunWizard\Settings\Personal::$urlGenerator is deprecated at /mnt/HDExtra/nextcloud-server/nextcloud/apps/firstrunwizard/lib/Settings/Personal.php#40
```

Signed-off-by: Bruno Cabral <cabral.brc@gmail.com>

Update lib/Settings/Personal.php

The interface is already in the namespace

Co-authored-by: Pytal <24800714+Pytal@users.noreply.github.com>
Signed-off-by: Bruno Cabral <cabral.brc@gmail.com>

lib/Settings/Personal.php

@@ -32,6 +32,8 @@ class Personal implements ISettings {
 
 	/** @var IConfig */
 	private $config;
+	/** @var IURLGenerator */
+	private $urlGenerator;
 	/** @var \OC_Defaults */
 	private $defaults;